American and Pakistani officials disagreed sharply Thursday about whether an Islamic school was struck by a U.S. drone, in an unusual attack that inflamed tensions over the CIA drone campaign.

According to Pakistani officials, three missiles were fired into a compound in Khyber Pakhtunkhwa province about 5 a.m. local time Thursday, a rare strike outside the Pakistani tribal areas near the Afghan border that are usually targeted by U.S drones.

Pakistani officials say the drone hit a "madrassa," or Islamic seminary, killing six people, including two teachers. The dead included Maulvi Ahmad Jan and Maulvi Hameedullah, who were top surrogates for Sirajuddin Haqqani, the second in command of the Haqqani militant group, which has ties to al-Qaida.